#include<iostream>
#include<string>
#include<list>
using namespace std;
class test1
{
public:
	int add(int&& x, int&& y)
	{
		return x + y;
	}
	//string& operator = (string && s)
	//{
	//	swap(s);
	//	return *this;
	//}
};

int main()
{
	test1 a;
	int j = a.add(20, 20);
	cout << j << endl;
	string test2;
	list<int> test3;
	test3.emplace_back(1);
	return 0;
}